Fuel injection system



Dec. 10, 1946. J. F. CAMPBELL FUEL INJECTION SYSTEM Filed Jail. 16. 1942 4` *Sheets-Sheet 1 Ecampgzz INVENTOR Den.` l0,l 1946; J. F. CAMPBELL 2,412,316

I FUEL. INJECTION SYSTEM Filed Jan. 1e. 1942 4 sheets-sheet 2 @XE e "JF Cam/06e!! Dec. l0, 1946.

J. F. CAMPBELL 1 FUEL.` INJECTION SYSTEM 4 Sheets-Sheet 5 Eild Jan. 1e. 194,2

Ecm/7662i INVENTOR ATTORNEY 4 Sheets-Sheet 4 INVENTR ATTORNEY Dec. 10, 1946. J. F. CAMPBELL `FUEL INJECTION SYSTEM Filed Jan. 16. 1942 a... i- -----ufsL L.

Y mw mais L 2,412,316 sont mlaorrou SYSTEM .lohn F. Campbell, Detroit, Mich., asslor to George M. Holley and Earl Holley Apo-lisation .lanuary lt, i942, Serial No. 4126A??? l (ci. its-37) Il Claims. l

The object of this invention is to inject volatile fuels or fuels containing air bubbles by means of a plunger into an internal combustion. engine. The specific object is to permit the bubbles of air and vapor to escape before injection of the fuel without interfering with the metering characteristics of the fuel injection pump. In fuels of the volatile type it is customary to use spark ignition and therefore, the time of ignition is not deter.- mined by the time of the fuelginjection. With such pumps, l' have found that it is desirable to have a fixed point of cut-obi prior to the ignition point and therefore, I regulate the amount of fuel by the variable point in the pumping stroke .of the pump when the escape of the surplus fuel and fuel carrying the vapor is prevented. As the plunger moves beyond the initial point the fuel is injected into the engine cylinder'until the 'fuel pressure is suddenly released.

In the drawings:

Fig. l shows diagrammatically the arrangement of all the elemente of my invention.

Fig. 2 shows the principal elementthe fuel puma-#on a section of plane 2--2 of Figs, 3 and '7.

Fig. 3 is a cross sectional plan view taken on plane 3 3 of Fig. 2.

Fig. e is a plan view teken on plane fisof Flg.2.

Fig. 5 is a plan view taken on plane --El of Fis'. FiFig. 6 is a plan view takenon plane of Fig. TI is a plan view taken on plane l-l of Fig.2.

Fig'. 8 is a sectional elevation of a modification ofFig.2.

Fig. 9 shows a cross sectional elevation of the vapor separator.

Fig. l shows diagrammatically the arrangements of the parts. Fuel leaves a tant: lo and is raised by apump l l to the fuel/air mixture ratio control l2 'which contains a fuel venturi iii. The fuel flows through a second venturi it to the vapor separator i5 whence it continues through a pipe t@ to the fuel entrance l@ of the metering pump il. Here a minor portion issues into a chamber @il where the vapor rises to the upper part of this chamber 3ft.4 The major portion of the fuel discharges through the'outlets it. The minor iraction of the fuel in the chamber lil is recirculated through the opening into the throat of the venturi 55 back to the vapor separator i5. This recirculation of the fuel ensures the elimination of entr aimed bubbles which disturb the metering characteristics oi the pump. The venturi it lil shown in the upper right hand corner of Fig. 1 is shown on a greatly enlarged scale but is actually of the same order of magnitude as the venturi 35 and has merely been enlarged so as to clearly indicate the nature of the restriction i3 which corresponds to the venturi liti as shown in my Patent No. 2281,@11, Fig. l2. ln Fig. l2 of this patent, the venturi fili is also shown in a large scale for a like reason. f

Considering the details shown in Figs. 2 to 7, lb is the fuel entrance as mentioned above, which delivers fuel to the cylinders itl. In these cylinclers' are two diameter-ed plungers 2@ reciprocated by theinclined swash plate 2l (Fig. 2) by means of the oblate spheroid 22 of .the plungers 2u. Each plunger has a tubular extension 23. ofV a smaller diameter than the main piston it. Each of these tubular extensions 23 engages with a movable yielciable abutment Zit. Each ci these yieldable abutments Wl is loaded by two springs 2t and 2l. These springs are located in a cham- A ber l@ and seat on a ange 2li which, in its turn, seats on the movable abutment tl.. The abutments of the springs are carried in c, cage 2t, on the lower ange of which the abutments 213 seat when the tubular extension 23 of the piston i@ is withdrawn into the cylinder le, es shown on the left hand side of Fig. 2. On the right hand side of Fig. 2, the piston lo ls shown elevated carryingwith it the tubular extension 23 which thusV compresses` the springs 2e, 2l by engaging with and moving the movable a-butments lt.

vThe cage 2B is reciprooated relative tothe cylinders le. Means for reciprocating it consists of a lever 2@ which rotates the shaft il@ which engages with the shaft ill. Grooves 3i! are provided on shaft @l adapted to move the pins-3 l, il which are mounted on the cage 23. The cage 2@ is thus moved when the shafts il@ and iii are rotated com'- pressing the springs 2l and 25. The spring 3S balonces in part the resistance of these springs 2t and 2l.

The rotation of the lever 2S thus determines the eective ich of the stroke of the two diametered plungers 2t when their tubular extensions 23 engage with the movable abutments 2t which is the moment when the plunger starts to deliver fuel to the nozzle, assuming that the piston 2o has covered the port il@ before the part t3 engages with the part le. l

The tubular extension 23 is perforated so that as the plunger E@ moves towards the movable abutments 2li any fuel containing air which is trapped in the annuler portion between the tubular extension te and the walls of the cylinder I9` discharges through the center of' the-tubular extension 23 and along the flutes of the guide to.;

the valve 24 which centers the valve 24 inside the central passage through the tubular extension 23. The moment the fuel is trapped in the cylinder I9, lthat is, the momentl the tubular extension 23 engages with the movable abutment 24, fuel is subjected to pressure and in Fig. 4 is shown a. number l of spring-loadedchebk valves 32. Fuel then discharges-through the passages 33 and flows down to the outletl passages I8, whence it is led to the nozzles on the engine (not shown). Now -the y is either vertical or horizontal, it

lthat the venturi yI4 is on the top side of the vertithe amount of fuel flowing through the passage chamber 34 which contains the springs 26 and 2l and the cage 28 communicates with the throat o-f the venturi I4 (Fig. 3), through a Passage 35 whence it is carried to the vapor separator I5 (Fig.3).

The fuel surrounding the springs 26 and 21' is agitated by the reciprocation of these springs,`

bubbles Aof vapor are released and these bubbles escape through the venturi I4 located above theK chamber 34.

The piston 20'is provided with a number of passage B which has an outlet port 51 and when this port` 51 rises, as shown on the right hand side of Fig. 2, it is in alignment with the cylinder port 58 and the discharge of the fuel abruptly ceases, the fuel escaping into the annulus 42.

In Fig. 8, the pump elements 20, 23 of Fig. 2 are modified as follows: The-part 50 of Fig. 8

l corresponds to the part 20 of Fig. 2 and the part 22 corresponds to and is identical with the part marked 22 of Fig. 2. The plunger 50 has a valve seat I which engages with a coned valve surl face 52 which forms the lower end of` a small piston 53. In the center of this small hollow valve is a passage 54 through which fuel can freely-discharge before valve 52 seats'on valve seat 5l'. The'small hollow-valve 53 carries the collar 55 which'seats on the shoulder 28 and this collar 55 is compressed against the shoulder 28 by the springs 26, 21, and the element 25 of Fig. 2, l which it is not necessary to show again as the function is the same. This shoulder 28 as already described can vbe moved by means of the pinsl 3|, 3l and the slots 30, 30. Hence the small.y ,hollow valve 53 forms a variable cut-ofi` for thel piston 50. A bushing 56 forms a bearing for the small piston 52.

An annular opening 51 in the piston 50 is connected by a-number of small holes 59 to the top face of thepiston 50. The result is that the small holes .59 serve.. as a by-pass so that when the piston 55 hascompleted its stroke and the annular opening 51 is in alignment with the'a'nnular port `58 of the cylinder, vthe discharge of the fuel from vapor escapes past the screen 61 'into the outlet 68 and then through a pipe 69 to the entrance I6. Of course, the vapor separator I5 can be built as an integral part of theupper casing- 70 a hollow cylindrical valve in alignment with said 35 of the fuel pump.

' Operation The device is mounted so that the venturi I4 is located above the vapor separating chamber.,` that is to say, whether the device shown in Fig. 2`

` small holes 'I communicating `with an annular l `from the annulus 42 and is first rejected through is arranged so cal or horizontal pump chamber. As the pump operates any bubbles that may collect in the- `chamber 3 4- are automatically removed tothe vapor separator I5 by means of the venturi I4. When the engine develops over 50% of its power,

35 is 20% or more of the total quantity of fuel thatv enters the fuel entrance I6. Hence this porl tion of the fuel is re-circulated and carries vwith it the bubbles of vapor and air to the vapor separator I5. By this means the cylinders are maintained full of .fuel so that the amount of fuel discharged.by, -feach nozzle isunlform, and the a p artial'vacuum and is most likely to release vapor bubbles, is rejected through the passage 54 (Fig. 8) and past the valve 24 (Fig. 2).

The reason the fuel flows into the chamber 34 and not back into the annular chamber 42 is because the pressure in the chamber 34 is maintained below the pressure in 42 by means of the venturi I2.

The mode of operation of the modification vshown in Fig. 8 and that of the device shown in Fig. 2 is substantially identical. In both cases, the escape of fuel into the chamber 34 is abruptly terminated when the cut-off valve seats and thereafter the fuel is compressed and discharged into the cylinder until such time as the groove- 57 in the plunger is in line with the annular groove 68 in the cylinder which determines the end of the injection stroke.

In the construction shown in Fig. 8, fuel enters the passage 54 and a portion of the fuel is then trapped between the piston 50 and the piston l53 when the valve seat 5I- engages the hollow valve 53 `having a'seat 52.. This portion of the fuel which is thus trapped is then injected through ya sure is suddenly and completely released. It fol-V lows, therefore, thatas the valve seats (5I in Fig. 8 and 24 in Fig. 2) are moved back and forth by the rotation of the lever 29, the time at which injection commences varies, but there is a fixed v point of cut-o determined by the instant when the slot 51 in the plunger comes into line with the cylinder port 58. l

`What I claim is:

l. In a fuel injectionv system for an internal combustion engine, a supply of fuel under presj sure, a vapor separator, a/ vapor separating tank,

a pump chamber, a fuel entrance communicating with said fuel supply and leading to said vaporseparator and communicating with said separating tank, a fuel outlet from said separator forniing the entrance to said pump chamber, means for maintaining a lower pressure in the separat-` ing tank than in thev fuel entrance to the pump chamber, a plunger, means for reciprocating said plunger, a valve seat integral -with said plunger,

seat of smaller diameter than said plunger and adapted to'permit'surplus` fuel to owthrough it to said separating tank, means for moving said valvel so 'as to engage withl said valve seat at different points in the stroke-of said plunger so as to interrupt the release of surplus fuel, yieldable means to permit the valve to move with said plunger after it has seated thereon, a relief passage in said plunger, a relief port in the side of thereby permits fuel to flow through the cylinder and past the valve to the separating tank under the pressure difference between the separating tank and the fuel entrance and whereby after this port is covered by the plunger on its in stroke,

fuel is then forced past the valve to the separating tank and whereby after the plunger engages with the hollow valvel fuel is trapped and thereby ejected through the outlet port past the check valve and this discharge continues until the relief port of the plunger engages with the inlet port of the cylinder when the discharge ofl fuel is abruptly terminated.

2. In a device as set forth in claim 1- in which the means for maintaining a lower pressure in the separating tank consists of a venturi in the fuel line and an opening in the throat of the venturi communicating with the separating tank so as to return the surplus fuel to be re-circulated,

3. In a fuel injection system for an internal combustion engine, a su'pply of fuel under pressure, a vapor separating tank, a vapor separator, a pump chamber, a fuel entrance communicating with said fuel supply and leading to said vapor separator and communicating with said separating tank, a fuel outlet ,from said separator forming the entrance leadingto said pump chamber, means for maintaining a lower pressure in the separating tank than in the fuel entrance to the pump chamber, a plunger, means for reciprocating said plunger, a hollow cylindrical extension of said plunger having a valve seat in the end, a valve engaging with said valve seat and in alignment therewith and adapted to permit surplus fuel lto flow from the pump chamber to the separating tank, the diameter of said cylindrical extension being less than the diameter of said plunger, adjustable means for locating said valve so thatit engages with said extension at different points in the stroke of the plunger, yieldable means permitting the valve to move with said extension after it has seated, a relief passage in said plunger, a relief port in the side of said plunger, an inlet port to the cylinder adapted tl. engage with the relief port in said plunger toward the end of the pressure stroke ofthe pump and also adapted to be uncovered by the end ofthe larger diameter of the plunger when it is near the end of its suction stroke, an outlet port from separating tank under the pressure difference between the separating tank and the fuel entrance and whereby after this port is covered by the plunger on its in stroke, fuel is then forced through the hollow valve to the separating tank and whereby after the. extension of the plunger engages with the valve fuel is trapped and thereby ejected through the outlet port past the check valve and this discharge continues until the relief port of the plunger engages with the inlet port of the cylinder when the discharge of fuel is abruptly terminated.

e. In a device as set forth in claim 3 in which. the means for maintaining a lower pressure in the separating tank consists of a venturi in the fuel line and' an opening. in the throat of the venturi communicating with the separating tank so as to return Athe surplus fuel to be re-circulated.

JOm F. CAB/IPBELL. 

